You’ve been training hard for a marathon – forcing yourself out of bed every morning, running progressively longer distances, building the strength, stamina and endurance for the big day, whilst following a strict diet to fuel up for the intensive training that’s underway. The rigorous physical activity and disciplined lifestyle should ensure that you end up losing weight steadily while on your way to acquiring a leaner and fitter physique. But, wait a minute—is your weighing scale suggesting otherwise?

Incredible as it may seem, cases where people who are training for a marathon end up gaining weight instead of the reverse are not unheard of. The reasons range from the accumulation of greater muscle mass to incorrect diet and training. If this is happening to you, it’s important to understand why, and take corrective action if necessary.

Why a marathon diet plan can cause weight gain

The three main reasons for weight gain during marathon training are the build-up of lean muscle, accumulation of glucose in the muscles, and overcompensation of calories.

Build-up of muscle mass: Intense physical activity of any kind leads to the decrease in body fat and the build-up of lean muscle. Since lean muscle is denser than fat it leads to weight gain, while ensuring that you look slimmer and healthier. This kind of weight gain isn’t unhealthy, so there’s no reason to worry.

Storage of glucose: As the body gets used to rigorous training, its capacity to store muscle glucose increases. This helps power the body during training. In fact, the glucose content in the muscles of a trained athlete may be three to four times higher than that of the average person. This, along with the fact that muscle glucose storage also leads to the retention of extra water in the body, results in weight gain.

Overcompensation of calories: This is one of the key reasons for weight gain; if excess calorie intake is causing your weight to surge, it’s imperative to take measures to correct the problem. The knowledge that one is undergoing an intense training programme often generates a perception that eating high calorie foods is alright—after all, what’s wrong with rewarding yourself with a small treat when you’re just back from a 20 km run? Except that such ‘small’ treats add to the calorie count, the outcome being weight gain.

The best way to control your weight while training

Following your prescribed diet, without getting swayed by temptations, is the key to preventing weight gain while training for a marathon. Here are some points to keep in mind:

Follow a balanced diet: While training for a difficult endurance sport such as a marathon, it’s vital to work under the supervision of professional trainers and dieticians. Stick to the diet prescribed by your nutritionist and don’t deviate under any circumstances. Avoid rewarding yourself with food in particular; such treats are a major reason for the overcompensation of calories leading to weight gain.

Drink plenty of water: Proper hydration not only helps regulate body temperature through sweating, but also prevents overeating. How? It’s not unusual for people to mistake thirst for hunger, and when that happens, you end up eating when all you needed was just a glass of water. This naturally adds to the calorie count.

Medical conditions: Weight gain while training for a marathon may also happen due to existing medical conditions. If you suspect that a health condition could be the underlying cause for your weight gain, speak to your coach or doctor immediately. 

The intense training required to prepare for a marathon may lead to certain changes in the body including weight gain. Since all weight gain isn’t necessarily bad, don’t rush to incorporate weight loss measures into your lifestyle. Consider other body composition parameters like fat percentage while assessing your fitness. A few steps such as avoiding refined food, following the instructions of your trainer, and reinforcing greater discipline into your life should help you curb unwanted weight gain.

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